Method of lining can ends



' March 16, 1943. J; HQTHERSALL 2,313,750

METHOD OF LINING CAN ENDS Filed June 15, 1940 ATTOR EY Patented Mar. 16, 1943 UNITED STATES PATENT A oF ic 2,313,750

Marnon or LININGCAN ENDS John M. Bothersall, Brooklyn, N. Y., assignor to i American Can Company, New York, N; Y., a

corporation of New Jersey Application June 15, 1940, semi No. 340,807

2 Claims. '(01. fs-so) The present invention relates to a method of lining can ends and the like and has particular reference toapplying a'-hot thermoplastic compound to the can ends.

In can manufacturing practices a common method of lining can ends includes depositingv a lining compound containing solvents in the curl of the end' and the solvents are then driven oil by heat in a drying step priorto assembling theend with a can. The instant invention contemplates eliminating this drying operation on can ends used for certain purposes, by applying a thermoplastic compound having no solvents of a volatile character, and which congeals when 1 applied to the can end but which also remains suificiently in a plastic condition so that it may be readily squeezed between the parts of a seam by the heat and pressure incident to uniting the can end to acan. An object therefore of the'invention is the provision of a method of lining can ends wherein a thermoplastic compound lacking volatile solvents is applied to the can end' while the compound is maintainedin heated condition following which the compound is congealed but remains sufliciently plastic so that the pressure and heat of seaming the can end to the can will spread the compound throughout the end seam parts, thus eliminating any necessity of drying the compound before uniting the can end with the can. 1

Another obj ect is the provision of such a method of lining can ends wherein the ends are cooled prior to application of the thermoplastic com- Figure 1 is a schematic sectional view of one form of apparatus for carrying out the steps of the instant method invention, parts being broken away: g

' Fig. 2 is an enlarged fragmentary. sectional view of an inverted conventional can end having a'thermoplastic compound applied thereto in ac- L can end to a can, the view showing only a portion of the can end and only a fragment of the upper end'of a can. 4

As a preferred embodiment of the invention can ends A either at room temperature or artificially cooled to below room temperature are lined with a heated thermoplastic lining compound. The hot compound is preferably deposited in the flange curl or peripheral sealing compound groove B of the can end in a narrow substantially semi-cylindrical ribbon as shown in Fig. 2. Such a compound may be a suitable gum mixture which does not contain any solvents which need to be driven oil by heat in order to dry and condition the compound for use.

One form of compound which is sometimes used contains 54 percent pontianac gum mixed. 35 percent of number 16 castor oil, 1 percent Titanox, and 10 percent glycerine.

Another form of compound contains 65 percent pontianac gum mixed, 19 percent of number 16 castor oil, 3 percent of castor oil and Titanox mixed, and 13 percent of AA castor oil.

Still another form of'compound contains 60 percent pontianac gummixed, 17 percent of number 16 castor oil, 3 percent of castor oil and .able manner in time with the other moving parts of the apparatus.

As the can end A rotates with the table I i the thermoplastic compound indicated by the numeral I6 is ejected'from a nozzle ll .disposed over the path of travel of the end flange curl B. The nozzle is connected to the lower end of a tube It which may be the lower end of a coil. 19 4 receiving the compound from any suitable source of supp y such as a tank or reservoir.

The coil i9 is disposed within acasing 21 having top and bottom cover plates 22 which cordance with the instant method invention; and

Fig. 3 is an enlarged sectional view of a conventional double seam uniting a compound lined enclose a steam chamber 23. The tube I! of the coil extends through-bosses 24 formed on the outside of the cover plates. Steam is circulated through the chamber and around the coil by way of an entrance pipe 26 and an exit pipe 2I. These pipes are threaded into bosses 28 which are formed on the cover plates 22. The

entrance pipe may lead from a suitable source of supply of steam and the exit pipe leads to any suitable -place of discharge for the used steam. It is this steam. that makes the lining compound hot while the latter flows through the coil 19. Thus as the can end rotates, a ribbon of hot thermoplastic compound issuing from the noz-' zle I1 is deposited in the curl B of .the can end where it takes the form substantially shown in Fig. 2. v

The thermoplastic nature of the compound is such that it will become of semi-plastic consistency as soon as its heat is dissipated. A can end at room temperature will cause a reasonably rapid congealing of the compound. However, this cooling action may be accelerated by further cooling the part of the can end on which the compound is deposited just before such ,deposit. Fig. 1 shows such a cooling step. While the can end rotates, the curlB opposite the position of lining is cooled by compressed air which is discharged from a'-nozzle 3! located over the path of travel of the curl. This nozzle is connected to a pipe 32 which leads toany suitable source of supply of compressed air.

The hot thermoplastic compound received on the cool curl B of the can end immediately con- I geals but remains in semi-plastic condition without any drying operation being performed thereon. The lined can ends may thus be immediately attached to cans or may be stored away or shipped for future use as desired.

Such a lined can end when made of metal is usually secured to a can'C (Fig. 3) in a double seam, a flange D of the can being interfolded with the can end curled flange in the usual manner. This interfolding is preferably done by a seaming roller and there results a double seam E which is hermetic. During this seaming operation considerable pressure is exerted on the flange parts and some heat is generated and s end for the reception of said compound thereon;-

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that'various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacri flcing all of the material advantages, the proc-. ess hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A method of lining can ends comprising flowing in molten form a thermoplastic lining compound containing no volatile solvents in the form of arelatively narrow raised ribbon to the flange portion of a can end while cooling said the compound being adapted immediately to congeal and thereafter remain in a sufliciently plastic condition to spreadand incorporate itself into a can and seam joint solely under the heat and pressure developedby the operation of seaming the end so lined to a can body, whereby to eliminate the necessity of first applying heat ,or otherwise evaporating volatile solvents in the lining compound prior to seaming the end so treated to the can body in a hermetic .joint.

2. A method of lining can ends and securing the same to a can body in a hermetic joint, comprising flowing in molten form a thermoplastic lining compound containing no volatile solvents in the form of a relatively narrow raised ribbon directly on the flange portion of a can end while cooling said flange portion for the reception of.

said compound thereon, the compound being adapted immediately to oongeal and thereafter remain in a sumciently plastic condition to spread and incorporate itself into a can end seam joint solely under the pressure and heat developed by the operation of seaming the end so lined to a can without the necessity for first applying heat or otherwise driving off and evapcrating volatile solvents in the lining compound, placing said lined can end ontothe flange of a can to be closed, and uniting said can and said can end in a seamed joint by exerting pressure on said flanges to produce an interfolded end seamcontaining said compound, said pressure and heat developed by the seaming oberation serving to spread said compound throughout the folds-of said seam to' constitute a hermetic joint.

JOHN M. HOI'HERSALL. 

